A forced sprayer (such as that for a perfume bottle) is known to be one which, in response to an external force, introduces a small amount of liquid from a container with which the sprayer is connected and sprays the liquid in an atomized form. Among various kinds of such sprayers the one which is mounted on an opening of a bottle and actuated to spray by being pressed is the most well-known. FIGS. 1-3 show several such press type sprayers, each of which comprises a press button A, a piston rod B, a housing C provided to enclose the opening of a bottle (not shown), a valve D, an internal sleeve E, a cylinder F, a spring G, a nozzle H, and a liquid introducing tube I. In use, the housing C encloses an opening of a bottle (not shown) and the liquid introducing tube I is inserted in the bottle and immersed in the liquid contained in the bottle. When the press button A is pressed down, the piston rod B moves downward along with the valve D within the cylinder F, and when the lower end of the valve D contacts the lower end of the cylinder F, a sealed compression chamber K is formed in the upper portion of the cylinder F, where a small amount of liquid flows in during the movement of the valve D. Further downward movement of the piston rod B reduces the volume of the chamber K and increases the pressure of the liquid in the chamber. When a back pressure in the chamber is larger than the resilient force of the spring G, the valve D is forced to make an instant downward movement such that the liquid in the chamber escapes through a gap formed between the valve D and the piston rod B and is sprayed in an atomized form through the nozzle H located near the press button A.
However, the aforementioned press type sprayers do not provide a satisfactory spraying effect. Whether a spraying effect is satisfactory or not is judged based on two considerations: (1) uniformness of atomization of the sprayed liquid, and (2) instant and sensitive response of spraying (i.e., a short time duration from the actuation of the press button to the actual spraying action from the nozzle). These two factors are determined by the response of the valve D. A slow response of the valve D prolongs the response time from the actuation of the press button to the actual spraying action from the nozzle, and consequently can not provide a sufficient force to spray a necessary amount of liquid in a very short instant. A weak spraying force could lead to ununiformness of atomization and degrade the spraying effect. If the liquid is perfume, a degraded spraying effect would severely deteriorate the quality of the perfume perceived by a consumer even if the perfume itself is of a high quality.
More specifically, the poor spraying effect of the conventional sprayers is resulted from a poor design of the back pressure area of the valve; the movement of the valve D in the chamber K can not result in a smooth upward flow of the liquid contained in the chamber, thereby lowering the sensitivity of the piston rod as well as reducing the amount and atomization effect of the sprayed liquid. As seen from the prior art valve D shown in FIG. 1, the back pressure area D1 thereof is of a step-slant design; hence, liquid pressure can not concentrate on the area, and moreover liquid can not accumulate on the area to provide a sufficient pressure. In the prior art valve D shown in FIG. 2, the back pressure area D2 is designed to be in the form of a reservoir, which may provide a function to accumulate liquid, but it is difficult for liquid to flow smoothly from the lower part of the chamber K upward to the back pressure area D2; consequently, the effect thereof is still poor. In the prior art shown in FIG. 3, the back pressure area D3 is provided with annular teeth, which may provide sufficient areas to receive liquid pressure, but it does still not provide a satisfactory accumulating effect for liquid on the area, and therefore the sprayer can still not provide a perfect spraying effect.